1. Field of the Invention
This invention relates to a process of converting high-boiling crude oils which have high contents, e.g., as high as 70 percent of non-distillable residue, and contain metals and asphaltenes to products similar to petroleum products in the presence of hydrogen donors and of molecular hydrogen at elevated temperature and pressure by donor solvent hydrovisbreaking.
2. Discussion of Prior Art
Heavy crude oils, tars recovered from tar sand, oil shale and the like often cannot be processed with conventional technologies.
If the heavy hydrocarbons have extremely large contents of high-boiling components, asphaltenes, heavy metals and/or elements of the arsenic group, the known processing methods are neither satisfactory nor sufficiently flexible as regards the distribution of yields and the removal of metal.
It has been proposed to process such raw materials by an expensive catalytic hydrogenation in the liquid phase and/or by a de-asphaltization in which asphaltenes are converted or removed, catalyst poisons are separated and products are obtained which can be subjected to known subsequent processing in existing plants. Those proposals involve the disadvantage that the catalytic hydrogenation in the liquid phase incorporates the need of regenerating the catalyst and that this can be accomplished only with great difficulty if the feedstock has extremely high contents of asphaltenes, metals and trace elements. The use of one-way-catalysts involves a loss of catalyst as well as high losses of hydrocarbon oil yields. Additionally the activity of the proposed one-way-catalysts is often inadequate and this can be compensated only by high reaction pressures and temperatures which results in decreases of yield and quality.
It is also known to de-asphaltize the heavy hydrocarbon oil for a recovery of hydrocarbon oils which are substantially free from asphaltenes and can be processed further. Those processes involve the disadvantage that the yields are greatly restricted and an excessively large asphalt fraction is formed which can be used only for a few purposes. Those proposals do not ensure the required removal of metal and trace elements if the feedstock has extremely high contents of asphaltenes, metals and/or other trace elements which constitute catalyst poisons (German Offenlegungsschrift Nos. 2,504,487; 2,504,488; 2,644,721 and 2,726,490).
It is an object of the invention to avoid these disadvantages involved in the prior art and to provide a simple process which can be carried out in a single step, if desired, and in conjunction with a high yield meets the quality requirements set forth.